Media Menu for the Data Center

Copper Fiber Face-off

Twinax           Augmented Category 6

Data centers evolved from mainframe computer rooms in the 1990’s. At that time 1000BASE-T was being used for high-speed 1 Gb/s applications. A mere decade later brought speeds of 10 Gb/s into fruition in the data center environment. A pre-cursor to the Ethernet protocol, known as Infiniband, utilized twinaxial, or “twinax,” which is a variation of coax cable, but with two conductors instead of one. Infiniband is a high-speed; low-latency architecture that is primarily used for interconnects between switches and servers. The distance is limited to 7-15 meters (server to server, server to SAN or server to switch). 

In 2004, an Ethernet  protocol for implementing 10 Gb/s applications was introduced with IEEE802.ak (10GBASE-CX4), which employs twinax. By 2006, 10GBASE-T offered a low-cost 10Gb/s alternative using twisted pair, Augmented Category 6 copper cabling out to 100 meters. For longer runs, 10GBASE-SR and LR over multimode and singlemode optical fiber became Ethernet’s alternative to Fibre Channel.
 
Today fiber, twisted pair and twinax are all being utilized in the data center space, depending on the application and distance. Whereas twinax has been losing ground to the more favorable twisted pair and fiber structured cabling architecture, twinax has its advantages as a viable interconnect due to its low latency, lower power consumption and no crosstalk.  On the flip side, twinaxassemblies are also more expensive than UTP assemblies. The following table shows the cable media choice, distance and current standards for 10 Gb/s.
 
10 Gb/s Media
10G Chart
 
A changing landscape
The ANSI/TIA-942 Telecommunications Infrastructure Standard for Data Centers focuses on the structured cabling and the schematic layout. Twisted pair, fiber optic and twinax are all recognized cable in this standard, depending on the application and of course, distance.
But the data center landscape is changing rapidly. Networks need to accommodate the key drivers of data center evolution, which include modularity, flexibility, increased bandwidth, and growing virtualization. Although history shows that network systems are upgraded every three years, cabling infrastructure and standards are written to support 2-3 generations of active equipment. I.T. departments building new data centers, expanding existing data center footprints, or updating racks of equipment all have to design a cabling and switching architecture that supports rapid changes and mobility, and accommodates transitions, especially since speeds are quickly moving from 10 Gb/s to 40 and 100-Gb/s.
Pre Term assembly 
IEEE 802.3ba standards’ Task Group is currently reviewing the needs for the transport of 40-100 Gb/s over Ethernet and have based much of their work on the channel distance of 100 meters. This group is focusing on laser-optimized multimode fiber, as the media of choice for future proofing today for 40 Gb/s and above, making OM3 the minimum recommendation. However, with its superior bandwidth and distance reach, OM4 is the highest performing multimode fiber defined to assure data transmission across these channels.   In addition, OM3 and OM4 multimode systems are still expected to be well below the cost of a total channel operating over a single mode fiber system.
 
So, the deciding factors for the right media for both today and tomorrow include distance, bandwidth and also the turnover expectations of the active equipment. If you are looking for short interconnects and a high bandwidth connections for today, twinax might fit the bill. But, as Ethernet standards continue to gain ground, more and more I.T. managers will be specifying twisted pair and fiber. Twisted pair is the most economical and therefore standards’ committees are examining copper, for a low-cost alternative to fiber. But, if 40 Gb/s or 100 Gb/s seems to be on the near horizon, your best bet is to specify OM4 multimode fiber. The use of fiber for your data server and storage farms and SANs guarantees application assurance and exploding bandwidths to come.
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Your Contact

Carol Oliver Berk-Tek Marketing Analyst
carol.oliver@nexans.com